Now sees first flight for new jet by the end of July.

TORONTO--Bombardier Inc.'s aerospace unit said Wednesday that it has pushed back the timeline for the first flight of its CSeries aircraft to allow for additional software upgrades, and now expects the maiden flight to occur by the end of July, or a month later than its most recent target.

The Montreal-based transportation-equipment giant said the software upgrades will allow "for improved system maturity and functionality" for the single-aisle jet. The delay highlights the company's conservatism, both...